Ripped and Torn Shoulders on Saw Blades- Part 2
In our last blog about Ripped and Torn Shoulders on a saw blade, we introduced the problem and gave some insight from some very knowledgeable saw filers on why the problem with ripped and torn shoulders may have been ocurring. In the last blog, we focused on possible causes that centered around heat being the most likely cause.
In this blog we are going to discuss other possible causes, such as machinery and how automatic brazing machines may have added to the problem of ripped and torn out shoulders.
Here is a little review and background about the problem:
Emily, here at Carbide Processors, got a call from a filer in Canada who had a problem with ripped shoulders. I talked about brazing which is about all I know. He thought there were other factors involved so I sent an email to some filers I had met and they passed it on. That is how I got the incredibly good answers below.
This is the problem the saw filers discussed.
Shoulders ripping out. Filer thinks it is below his chill line. Problem only occurs with Fir. It does not occur when they cut Hemlock. As near as he can tell any kind of Fir causes problems. Saws from X company which can’t give him an answer. Kaehny automatic brazer.
Here are some of the Saw Filers’ responses:
Mike West- Cascade Hardwoods:
Hi Tom, I just saw your post about the automatic brazing machine. Holy crap! That wasn’t broken off shoulders, it was ripped out teeth, right down to the quick.
We had such a serious problem with the annealing cycle on our Stellite© tipper that we did away with the induction annealer and went to a separate stand-alone propane annealer. It saved us thousands of teeth a month not to mention downtime for saw changes. It enabled us to eliminate the annealing cycle in our tipper to tip saws faster and we rarely if ever lose a tooth or shoulder anymore.
Actually faster now, especially if you include the extra saws we aren’t doing. The annealer we got was from Larry Spielman down at HS International in Vancouver, but he has since sold all the patents to Wright Machine and they are making one now I believe.
Not to fault Armstrong, there are just too many variables with the induction annealing. Dirty contacts, voltage surges and drops, oil on the saw blade. Recipe for failure.
When we lose a tip or, down into the tooth, we check out the annealer. It should be dull red. Then we might do a bend test (using a junk saw). Then we head down to the machine. We have seen surge problems on the gang feed. We have seen them double stack 2 inch boards into the board edger. It is usually an abuse problem or a mechanical issue. (You hand over your best suitcase to a pissed off gorilla and tell him to be careful with it……such is the life of a saw……)
Automatic machinery isn’t
I have just spent a couple of hours helping a gentleman in Canada with a saw failure problem. This is a sawmill and the shoulders are ripping off the saws.
They are using a Kaehny automatic brazor with an automatic annealer. These are good machines and they work well.
The problem that comes in is the meaning of the term automatic. They may run automatically but they still need some maintenance.
Over the years I have seen three problems with these machines.
The lens or cover over the heat sensor becomes clouded over due to the flux fumes. As it gets cloudy it lets less light through so the sensor reads lower. This means that the saw steel gets overheated and thus becomes brittle.
There is an induction coil and the induction coil is supposed to put the heat into the carbide saw tip. Often this coil will be moved or changed so that the bottom lines up with the saw tip that the top lines up with the saw plate. This can put too much heat into the saw plate. A simple solution to this is to spread the top part of the coil out so it is further away from the plate. It is generally pretty easy to gently bend the top of that coil out. If you bend it so that the top of the coil is about three times as far from the saw plate as it used to be then you have cut the amount of heat going into the plate 1/9 th.
The third problem I have seen is that the automatic annealor is set to restore the steel to the proper temper but it depends on the steel having been heated to the proper temperature during brazing or welding. If the steel is overheated during brazing or welding then the dealer will still run the same cycle it always has. Because of steel is overheated the standard annealing cycle will anneal enough and the saw steel will still be brittle.
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